A 71-year-old taxi driver, who hit his lawyer's wife on the head with a bicycle chain and set fire to the law office with her still inside, was on Friday (April 1) sentenced to the maximum 10 years' jail.

Govindasamy Nallaiah, who was in a fee dispute with the lawyer, was charged originally with murder but eventually found guilty in February by the High Court of a lesser charge of culpable homicide not amounting to murder.

He originally faced life imprisonment or death for murder when, in a very rarely invoked provision, he was charged with committing an act he knew was "so imminently dangerous that it must in all probability cause death".

Govindasamy did not dispute that he started the fire, which killed Madam Low Foong Meng in her husband's office on the sixth floor of the Afro Asia Building in August 2011.

Judicial Commissioner Hoo Sheau Peng had found that Govindasamy had gone to the office with ill intent and that his dangerous act of setting fire to the office was likely to cause death.

But, she said, it had not been proven beyond reasonable doubt that Govindasamy's act "was so imminently dangerous that it would in all probability cause death".

In sentencing, she agreed with prosecution that it was one of the more serious instances of culpable homicide. Govindasamy's attack was "deplorable" and caused victim to suffer multiple injuries, she said.

The court had heard during the trial last year that Govindasamy owed Mr Rengarajoo Rengasamy Balasamy, a childhood friend, $38,000 in legal fees incurred when the lawyer represented him in a 2002 corruption trial.

He was given a deadline to pay up by Aug 10, 2011. That morning, he went to Mr Rengarajoo's office and tried to negotiate with Madam Low.

He took out a bicycle chain and padlock and hit her on the head until she collapsed. He then used a lighter to set some files on a table on fire before fleeing, leaving Madam Low inside.